A private security guard patrolling Millennium park on a Segway Personal Transporter, Chicago, USA.
Private security guards are part of what is now termed the wider Police Family. The Family includes, community volunteers, private security guards and other undefined 'authority figures' who can act alongside the police and issue fixed-penalty notices.
For more on this topic please see Anna Minton's excellent book Ground Control: Fear and happiness in the twenty-first-century-city, Penguin books, 2009